One of the key arguments that Darwin makes in his On the Origin of Species concerns the Struggle for Existence. Individuals are constantly locked in competition, whether with other members of the same species, different species that may occupy the same or similar ecological niche, or environmental factors. Those organisms that survive then reproduce and pass their traits onto the next generation. Those that do not win out die, and if this concept is applied to entire species, it may result in extinction due to a failure to adapt to changing conditions.
The most important aspect of the struggle involves the environmental limits that all organisms must face. These restrictions, which encompasses resources such as food, predator and parasite interactions, and climate, drive natural selection. Without these forces at work, Darwin’s theory would not stand. Since abundance reduces conflict while scarcity leads to competition, nature provides the pressure that fuels the engine of evolution.
In one of his examples, Darwin highlights the difference between artificial and natural selection. Man rarely favors one character over another; “he feeds a long and a short beaked pigeon on the same food; he does not exercise a long-backed or long-legged quadruped in any peculiar manner; he exposes sheep with long and short wool to the same climate” (83). These traits could all be selected for in a population of wild animals. Man then acts as an equalizer whereas nature would preferentially pick certain individuals over others.
In a larger scope, all species would continue to increase in number if they were able. The fact that we do not see an ever increasing amount of rabbits or wolves or eagles suggest that their population is kept in check by what the environment can support. Darwin postulates that growth is capped by the amount of readily available food and by the increased spread of parasites and disease among dense groups. Other facts include a corresponding rise in predator numbers, which all feeds into the Struggle.
This same concept can be applied to humans. Darwin was influenced by the work of Thomas Malthus, who wrote of the limits of population growth among mankind. Although society has thus far managed to avoid the famine, chaos, and destruction that would accompany global overpopulation, our technological innovation can only take us so far. There comes a point where all the pesticides and GMO crops and livestock cannot sustain the trajectory of humanity. We must face up to the challenges of climate change as well, and change our habit of burning recklessly burning fossil fuels and continued pollution. Otherwise, these selection pressures will soon act on us in our own Struggle for Existence.
I enjoyed your post, you did a very nice job summarizing the main points in Darwin’s, On the Origin of Species. However, I disagree with one of your points. You wrote:” In one of his examples, Darwin highlights the difference between artificial and natural selection. Man rarely favors one character over another; “he feeds a long and a short beaked pigeon on the same food; he does not exercise a long-backed or long-legged quadruped in any peculiar manner; he exposes sheep with long and short wool to the same climate” (83). These traits could all be selected for in a population of wild animals. Man then acts as an equalizer whereas nature would preferentially pick certain individuals over others.”
Man often favor one characteristic over another; otherwise we would have pet wolves, not pet dogs, and definitely not hundreds of choices of dog breeds. Although it may be true that we treat domesticated animals the same environmentally, we do control the reproduction aspect of what would otherwise be controlled by natural selection. Rather than the inability to reproduce being caused by death (influenced by environmental pressures, as in Darwin’s natural selection theory), animals with undesirable traits are not allowed to breed by human choice (as in a dog breeder who is trying to create a smaller animal who only allows the smallest of the litter to procreate). Darwin wrote: “As man can produce and certainly has produced a great result by his methodical and unconscious means of selection . . . Man can act only on external and visible characters,” (82) and by this I believe his intention was to illuminate the limit of man’s ability to affect only the physical of outcome of his evolutionary tinkering, whereas nature has the time, patience and ability to affect all aspects of an organism’s evolution.
I agree that we must face the climate changes with more focus and determination, but I believe nature has been at war with us since the first time an ape decided to walk bipedally (and even more so before that). Selective pressure has always been clouding over us like a heavy rain. Humans have only just been better at adapting, but that still doesn’t stop natural selection from causing destructive storms like Sandy, or potential meteorites like the one that ended the dinosaurs. Still, that doesn’t mean the intelligence we have can’t make a difference to end the very chemicals and products that could ultimately be our meteorite to our epoch. So I hope climate change will be recognized in a more crucial way in the future, and we can end our anthropocentric ways.
Nice post. I find it interesting where you talk about Darwin’s thoughts on artificial and natural selection. I would argue that humans pose the largest source of artificial selection by the animals we choose to breed, the livestock we choose to raise and consume, the plants we choos to grow. Hunters often select for larger game animals, often times alpha males which hold a keystone position in a larger group. Through this artificial selection by humans we are decreasing the overall size of wild game animals be removing those genes from the community. Agricultural practices seem to be the most dramatic. I wouldn’t assume that corn grew indigenously over the entire state of Kansas, yet we have selected to grow it. As environmental pressures to support our own population, we seem to further select and manipulate our surroundings.